78 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
4709, are not marked for locality, but probably came from Ohio, Wisconsin, 
or Michigan, and are really his types. They are exactly the size of ordinary 
leucopus; the tail a little shorter, relatively, than the average of leucopus, but 
not shorter than is often found in Zeucopus; and they are colored exactly as 
in gossypinus, the upper parts being very dark, the under impure white, and 
the tail indistinctly bicolor. 
Here, then, is an exactly intermediate form between leucopus and gossy- 
pinus, proving that the latter cannot properly be regarded as specifically 
different. from the former. 
It is obviously a matter of indifference where we make our break in the 
chain between the two; i.e., whether we assign the links “‘cognatus” to one or 
the other. Practically, however, it will be found most convenient to assign 
“cognatus LeC.” to leucopus, so that we only recognize the extreme of differ- 
entiation in gossypinus. This course is the more commendable, since “cog- 
natus Baird”, based as above explained, is assuredly /eucopus. 
TaBLE XVIII.—List of specimens of HESPEROMYS LEUCOPUS var. GOSSYPINUS. 
rc) 
5 Locality. Received from. iS 2 3 2 Retnre oe 
2 em ifm seth oes specimen, 
5 ar| 2 
A iS 3) 
A705 || Georgia .-.-..-.----- ----.--- Jo ieContemnes-i-==— =e =— 4.00 | 2.90 | 0.86 | Dry. 
ATL ees == (1D peeode Cosnecobeecceca|lsscece Gimeno a noatoeseincic oe 4.25 | 2.50 | 0.90 | Dry. 
Gt eee saat) - 2 aep ers Hoosececesee Boece tUs ca coserocco ese: ace 4.50 | 2.05 | 0.90 | Dry. 
ABT | pecans GO ssesno cssoctescssesee IDEs GeOShenia= === sees iae 3.50 | 3.00 | 0.88 | Alcoholic. 
10086 | ----. GG soso ccon ctobostce seca|bansee dot sseniee-asee ee eens] Os 90M ee OUR On eye Alcon lcs 
1361 | South Carolina ...... -....--- Wi. Coopers...<2- 3 n50c2s25=25)/ 451004), 2235 ,0 80h Dry. 
8537 | West Kansas* ----.----.----- AS Crocker 2 co50 ee = === = -= a= 4.50 | 3.00 | 0.90 | Dry. 
*We hesitate in the determination of this specimen, since part of its size is due to overstuffing ; 
the under parts are white, and the tail sharply bicolor; the locality, too, is against the supposition that 
it is gossypinus ; and it is accompanied by other Kansas specimens that we cannot determine, and some 
that are certainly pure leucopus. In the length of the feet, however, and in general coloration, it seems 
to agree better with gossypinus than with true leucopus. Dr. Gesner’s specimens, likewise, we refer here 
on account of locality and their large size, though the mouth, feet, and tail underneath, are very pure 
white, and the under parts nearly so. (These specimens are both males, and exhibit the maximum 
development of the testes we have ever seen in the species. The glands form an immense bulging mass 
on the nates, about $ long by } wide, of flattened, oblong shape, quite sharp-pointed behind, and mostly 
divided by a deep median raphé.) 
